C实现固定大小对象池

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typedef struct common_obj_pool  common_obj_pool;typedef struct common_obj_node  common_obj_node;struct common_obj_pool {    uint    count;  //total num    uint    size;   //per size    uint    free;   //unused num    int     head;   //insert pos    int     tail;   //delete pos    uint    len;    //buffer len    void    *ptr;   //buffer addr};struct common_obj_node {    int     status;  //0:unuse, 1:inuse    int     next;  //>=0:next, -1:tail, -2:inuse    void    *data;  //user data};#define COM_OBJ_NODE_HEADL  (sizeof(common_obj_node)-sizeof(void*))#define COM_OBJ_NODE_SIZE   (COM_OBJ_NODE_HEADL + (pool->size))int common_obj_pool_init(common_obj_pool *pool, uint count, uint size){    int i;    common_obj_node *obj;    if(pool == NULL || count < 2 || size < 0)        return EINVAL;    pool->count = count;    pool->free = count;    pool->size = size;    pool->head = 0;    pool->tail = count-1;    pool->len = count*COM_OBJ_NODE_SIZE;    pool->ptr = malloc(pool->len);    if(pool->ptr == NULL)        return errno;    obj = pool->ptr;    for(i=0; i<count; i++){        obj->status = 0;if(i == count-1)obj->next = -1;elseobj->next = i+1;        obj = (void*)obj + COM_OBJ_NODE_SIZE;    }    return 0;}int common_obj_pool_destroy(common_obj_pool *pool){    free(pool->ptr);    memset(pool, 0, sizeof(common_obj_pool));    return 0;}int common_obj_malloc(common_obj_pool *pool, void **ptr){    common_obj_node *obj;    if(pool == NULL)        return EINVAL;    if(pool->free <= 0)        return ENOMEM;    obj = pool->ptr + (pool->head)*COM_OBJ_NODE_SIZE;    if(obj->status != 0)        return EFAULT;    pool->head = obj->next;    pool->free--;    obj->status = 1;    obj->next = -2;    *ptr = &obj->data;    memset(*ptr, 0, pool->size);    return 0;}int common_obj_free(common_obj_pool *pool, void *ptr){    int index;    common_obj_node *obj, *tail;    if(pool == NULL || ptr == NULL)        return EINVAL;    obj = ptr - COM_OBJ_NODE_HEADL;    if(obj->status != 1)        return EFAULT;    index = ((void*)obj - pool->ptr) / COM_OBJ_NODE_SIZE;    <pre code_snippet_id="605188" snippet_file_name="blog_20150215_1_5241167" name="code" class="cpp">    if(pool->head < 0)        pool->head = index

else{tail = pool->ptr + (pool->tail)*COM_OBJ_NODE_SIZE; tail->next = index;} pool->tail = index; pool->free++; obj->status = 0; obj->next = -1; return 0;}

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